夏祭り (Natsumatsuri) is a cover of Jitterin' Jinn's enduring 1990 summer anthem, performed by the vocalist ろん (Lon) for the maimai rhythm game series. The original, written and composed by frontman Jinta Hashi and released as Jitterin' Jinn's fourth single on August 29, 1990, has become one of Japan's most recognizable summer festival songs, covered countless times across decades. Lon's rendition brings the track into the SEGA rhythm game ecosystem with a bright, faithful vocal delivery that captures the song's nostalgic longing for a summer love set against the backdrop of fireworks, cotton candy, and crowded festival streets. The cover debuted in maimai PiNK PLUS on August 11, 2016, as a POPS & ANIME category entry. Its Expert chart was designed by 如月 ゆかり (Yukari Kisaragi), while the Master chart, which settled at level 11 after several version adjustments, was handled by しろいろ (Shiroiro). The track later crossed over into CHUNITHM AIR at that game's launch, making it one of the few songs playable in both SEGA arcade rhythm titles simultaneously. In Asian English-localized builds, the song appears under the title "NATSUMATSURI" with the artist listed as "Jitterin' Jinn [covered by Lon]." 夏祭り was removed from Asian maimai DX cabinets starting with the スプラッシュ (Splash) edition and from Chinese cabinets beginning with 舞萌DX 2021, making it a legacy track unavailable on current arcade builds. Lon's cover has never been released on any commercial soundtrack, adding to its status as a time-limited, in-game-only artifact.